1. Field of the Invention
The present invention relates to an electrical connector, and particularly to a high density electrical connector having a plurality of circuit boards for high speed signal transmission.
2. Description of Related Art
Electrical connectors are used in many electronic systems. As miniaturization of the electronic systems becomes more prevalent, the dimensions of the connector itself decrease but the number of signal circuits routed through the connector increases. This results in an increasing number of signals in the limited space of the connector. As the signal circuits are spaced closer and the transmission speed of the signals increases, electromagnetic inference (EMI) and the crosstalk become a serious problem.
Accordingly, electrical connectors are equipped with shielding to attempt to shield each signal from EMI from neighboring signals. This shielding can be a conventional mechanical shield or an electrical shield in the form of a ground line. U.S. Pat. Nos. 5,066,236 and 5,104,341 each disclose a receptacle connector having shielding members. Cross-talk shield members are insertable into the rear of the connector housing to shield adjacent vertical rows of terminals from crosstalk, while upper and lower shield members are insertable over the assembly to shield the assembly from EMI. The upper and the lower shielding members provide resilient fingers for contacting with grounding contacts of a mating header to thereby establish a grounding circuitry therebetween. However, the arrangement of positioning the cross-talk shield members between the adjacent rows of the terminals reduces the effective signal density. Significantly, the employment of the upper and the lower shield members complicates the manufacture of the connector as well as the assembly thereof.
U.S. Pat. No. 5,433,617, issued to Morlion et al., discloses an electrical connector assembly. The connector assembly comprises a header connector and a receptacle connector mounted on respective printed circuit boards, wherein the header connector provides first shielding plates while the receptacle connector provides side-by-side positioned, ground contact plates and a second shielding plate. Electrical connections and mechanical supports are established between corresponding parts of the first shielding plates, the second shielding plate and the ground contact plates. Specially, in the coupled position of the assembly, the first shielding plates of the header provide contact springs simultaneously engaging the edges of the ground contact plates and the second shielding plate of the receptacle. Further, the first shield plates, the ground contact plates and the second shield plate have contact elements contacting corresponding conductors of the printed circuit boards on which the header and the receptacle are respectively mounted. Thus, the grounding circuits of the assembly are established. Moreover, in an alternative embodiment of the patent, a third shield plate is even provided. Obviously, the connector assembly as described above is unsuitable for mass-produce due to complicated manufacturing process and assembling process, both of which increase the cost.
U.S. Pat. No. 6,520,803, issued to Dunn, discloses a receptacle connector. At least one shielding plates are arranged between adjacent two rows of contact elements. A shielding member is attached on assembled connector housing members. The shielding member includes a plurality of cantilevered deflectable hooks received in corresponding recesses formed in the slender edges of the shielding plates to achieve a shielding purpose. It should be noted that in order to ensure a reliable connection between the shielding plates and the shielding member, the hooks and the recesses must be shaped to have the special configuration as disclosed in the patent, which results in the difficulty of manufacturing the connector.
U.S. Pat. No. 5,980,321, issued to Cohen et al., discloses a receptacle connector comprising a plurality of wafers side-by-side stacked and a metal stiffer holding the wafers in a required position. Each wafer is made in two pieces, a shield piece and a signal piece. The shield piece is formed by insert molding housing around a front portion thereof. The signal piece is made by insert molding housing around contacts. Further, in order to hold each wafer in the required position without rotation, three connection points are established between the metal stiffer and the wafer. The connection comprises projections formed on the wafer and corresponding slots defined in the stiffer. It should be noted that the projections must be accurately aligned with corresponding slots, respectively, thereby complicating the manufacture of the connector as well as the assembly thereof.
Hence, an improved electrical connector is required to overcome the disadvantages of the related art.
Accordingly, a first object of the present invention is to provide a high density electrical connector having enhanced electrical performance with a simplified configuration.
A second object of the present invention is to provide a high density electrical connector that can be easily manufactured and assembled.
In order to achieve the objects set forth, a high density electrical connector in accordance with the present invention comprises a dielectric housing defining a plurality of parallel slots, a plurality of terminals arranged in rows in the slots, and a plurality of parallelly arranged circuit boards received in corresponding slots of the housing. The terminals have contacting beams electrically connecting with conductive traces of the circuit boards, and tail portions for electrical connection to a printed circuit board on which the connector is mounted. A shield member substantially encloses the housing and the circuit boards. The circuit boards are retained by and between the housing and the shield member.
According to one aspect of the present invention, the shield member comprises a plurality of inwardly extruded lances not only separating adjacent circuit boards for mechanical consideration but also electrically contacting with the circuit boards for electrical consideration.
According to another aspect of the present invention, the circuit board has a mounting portion with the terminals connected thereto, and a mating portion with differential pairs of signal pads on one side thereof and grounding pads on two opposite sides thereof. Plural grounding traces electrically connect with the grounding pads and plural differential pairs of signal traces electrically connect with corresponding signal pads. The signal traces are arranged on the same side with the signal pads. The signal traces of the differential pair extend from corresponding signal pads adjacent innermost edges thereof to the mounting portion.
According to still another aspect of the present invention, each row of the terminals comprises plural differential pairs of signal terminals and plural pairs of grounding terminals. The pairs of the signal and the grounding terminals are alternatingly arranged. Each terminal further comprises an intermediate portion interconnecting the contacting beam with the tail portion. The contacting beams of the differential pair of the signal terminals extend upwardly from the intermediate portions adjacent innermost edges thereof.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.